BUG: make sure that the multi-index is lex-sorted before passing to _lexsort_indexer (GH8017)
BUG: sparse repr of multi-index frame with a FloatIndex as a level was incorrect
Merge pull request #8282 from jreback/sort

BUG: make sure that the multi-index is lex-sorted before passing to _lexsort_indexer (GH8017)